Re: [dpdk-dev] [PATCH 2/3] net/i40e: add runtime option to disable vector rx

["Ergin, Mesut A" <mesut.a.ergin@intel.com>]

> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> Sent: Thursday, May 16, 2019 1:17 AM
> To: Ergin, Mesut A <mesut.a.ergin@intel.com>; Xing, Beilei
> <beilei.xing@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 2/3] net/i40e: add runtime option to disable
> vector rx
> 
> 
> 
> On 5/16/19 6:28 AM, Mesut Ali Ergin wrote:
> > Vector RX functions are not at feature parity with non-vector ones and
> > currently the vector RX path is enabled by default. Hence, the only
> > option to force selection of non-vector variants and be able to retain
> > functionality is to disable vector PMD globally at compile time via the
> > config file option.
> >
> > This patch introduces a new runtime device config option named
> > disable-vec-rx to allow users to limit the driver to make a choice among
> > non-vector RX functions, on a per device basis. This runtime option
> > defaults to a value of zero, allowing vector RX functions to be
> > selected (current behavior). When disable-vec-rx=1 is specified for a
> > device, even if all the other requirements to select a vector RX
> > function are satisfied, the driver will still pick one out of the
> > appropriate non-vector RX functions.
> >
> > Signed-off-by: Mesut Ali Ergin <mesut.a.ergin@intel.com>
> > ---
> >   doc/guides/nics/i40e.rst       | 14 +++++++++
> >   drivers/net/i40e/i40e_ethdev.c | 70
> +++++++++++++++++++++++++++++++++++++++++-
> >   drivers/net/i40e/i40e_ethdev.h |  1 +
> >   drivers/net/i40e/i40e_rxtx.c   |  4 +++
> >   4 files changed, 88 insertions(+), 1 deletion(-)
> >
> > diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> > index a97484c..532cc64 100644
> > --- a/doc/guides/nics/i40e.rst
> > +++ b/doc/guides/nics/i40e.rst
> > @@ -183,6 +183,20 @@ Runtime Config Options
> >
> >     -w 84:00.0,use-latest-supported-vec=1
> >
> > +- ``Disable RX Vector Functions `` (default ``vector RX enabled``)
> > +
> > +  When config file option for the vector PMD is enabled, vector RX functions
> may
> > +  be the default choice of the driver at device initialization time, if certain
> > +  conditions apply. However, vector RX functions may not always be at
> feature
> > +  parity with non-vector ones. In order to allow users to override vector RX
> > +  function selection behavior at runtime, the ``devargs`` parameter
> > +  ``disable-vec-rx`` is introduced, such that
> > +
> > +  -w DBDF,disable-vec-rx=1
> > +
> > +  would force driver to limit its choices to non-vector RX function variants for
> > +  the device specified by the DBDF.
> > +
> >   Vector RX Pre-conditions
> >   ~~~~~~~~~~~~~~~~~~~~~~~~
> >   For Vector RX it is assumed that the number of descriptor rings will be a
> power
> > diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
> > index cab440f..19fbd23 100644
> > --- a/drivers/net/i40e/i40e_ethdev.c
> > +++ b/drivers/net/i40e/i40e_ethdev.c
> > @@ -44,6 +44,7 @@
> >   #define ETH_I40E_SUPPORT_MULTI_DRIVER	"support-multi-driver"
> >   #define ETH_I40E_QUEUE_NUM_PER_VF_ARG	"queue-num-per-vf"
> >   #define ETH_I40E_USE_LATEST_VEC	"use-latest-supported-vec"
> > +#define ETH_I40E_DISABLE_VEC_RX	"disable-vec-rx"
> >
> >   #define I40E_CLEAR_PXE_WAIT_MS     200
> >
> > @@ -410,6 +411,7 @@ static const char *const valid_keys[] = {
> >   	ETH_I40E_SUPPORT_MULTI_DRIVER,
> >   	ETH_I40E_QUEUE_NUM_PER_VF_ARG,
> >   	ETH_I40E_USE_LATEST_VEC,
> > +	ETH_I40E_DISABLE_VEC_RX,
> >   	NULL};
> >
> >   static const struct rte_pci_id pci_id_i40e_map[] = {
> > @@ -1263,6 +1265,68 @@ i40e_use_latest_vec(struct rte_eth_dev *dev)
> >   	return 0;
> >   }
> >
> > +static int
> > +i40e_parse_disable_vec_rx_handler(__rte_unused const char *key,
> > +				const char *value,
> > +				void *opaque)
> > +{
> > +	struct i40e_adapter *ad;
> > +
> > +	ad = (struct i40e_adapter *)opaque;
> > +
> > +	switch (atoi(value)) {
> > +	case 0:
> > +		/* Selection of RX vector functions left untouched*/
> > +		break;
> > +	case 1:
> > +		/* Disable RX vector functions as requested*/
> > +		ad->rx_vec_allowed = false;
> > +	break;
> > +	default:
> > +		PMD_DRV_LOG(WARNING, "Value should be 0 or 1, set it as
> 1!");
> 
> You may want to propagate the error here.
> 
Agreed, done and queued up for v2.

> > +	break;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +int
> > +i40e_disable_vec_rx(struct rte_eth_dev *dev)
> > +{
> > +	struct i40e_adapter *ad =
> > +		I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
> > +	struct rte_kvargs *kvlist;
> > +	int kvargs_count;
> > +
> > +
> > +	if (!dev->device->devargs)
> > +		return 0;
> > +
> > +	kvlist = rte_kvargs_parse(dev->device->devargs->args, valid_keys);
> > +	if (!kvlist)
> > +		return -EINVAL;
> > +
> > +	kvargs_count = rte_kvargs_count(kvlist, ETH_I40E_DISABLE_VEC_RX);
> > +	if (!kvargs_count) {
> > +		rte_kvargs_free(kvlist);
> > +		return 0;
> > +	}
> > +
> > +	if (kvargs_count > 1)
> > +		PMD_DRV_LOG(WARNING, "More than one argument \"%s\"
> and only "
> > +			    "the first invalid or last valid one is used !",
> > +			    ETH_I40E_DISABLE_VEC_RX);
> > +
> > +	if (rte_kvargs_process(kvlist, ETH_I40E_DISABLE_VEC_RX,
> > +				i40e_parse_disable_vec_rx_handler, ad) < 0) {
> > +		rte_kvargs_free(kvlist);
> > +		return -EINVAL;
> > +	}
> > +
> > +	rte_kvargs_free(kvlist);
> > +	return 0;
> > +}
> > +
> >   #define I40E_ALARM_INTERVAL 50000 /* us */
> >
> >   static int
> > @@ -1795,6 +1859,9 @@ i40e_dev_configure(struct rte_eth_dev *dev)
> >   	ad->tx_simple_allowed = true;
> >   	ad->tx_vec_allowed = true;
> >
> > +	/* Check if users wanted to disable vector RX functions */
> > +	i40e_disable_vec_rx(dev);
> 
> Ditto, error should be propagated.
> 
Likewise, agreed, done and queued up for v2.

> > +
> >   	/* Only legacy filter API needs the following fdir config. So when the
> >   	 * legacy filter API is deprecated, the following codes should also be
> >   	 * removed.
> > @@ -12790,4 +12857,5 @@ RTE_PMD_REGISTER_PARAM_STRING(net_i40e,
> >   			      ETH_I40E_FLOATING_VEB_LIST_ARG "=<string>"
> >   			      ETH_I40E_QUEUE_NUM_PER_VF_ARG
> "=1|2|4|8|16"
> >   			      ETH_I40E_SUPPORT_MULTI_DRIVER "=1"
> > -			      ETH_I40E_USE_LATEST_VEC "=0|1");
> > +			      ETH_I40E_USE_LATEST_VEC "=0|1"
> > +			      ETH_I40E_DISABLE_VEC_RX "=0|1");
> > diff --git a/drivers/net/i40e/i40e_ethdev.h b/drivers/net/i40e/i40e_ethdev.h
> > index 9855038..906bfe9 100644
> > --- a/drivers/net/i40e/i40e_ethdev.h
> > +++ b/drivers/net/i40e/i40e_ethdev.h
> > @@ -1248,6 +1248,7 @@ int i40e_config_rss_filter(struct i40e_pf *pf,
> >   		struct i40e_rte_flow_rss_conf *conf, bool add);
> >   int i40e_vf_representor_init(struct rte_eth_dev *ethdev, void *init_params);
> >   int i40e_vf_representor_uninit(struct rte_eth_dev *ethdev);
> > +int i40e_disable_vec_rx(struct rte_eth_dev *dev);
> >
> >   #define I40E_DEV_TO_PCI(eth_dev) \
> >   	RTE_DEV_TO_PCI((eth_dev)->device)
> > diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> > index 1489552..7e66f59 100644
> > --- a/drivers/net/i40e/i40e_rxtx.c
> > +++ b/drivers/net/i40e/i40e_rxtx.c
> > @@ -1736,6 +1736,10 @@ i40e_dev_rx_queue_setup_runtime(struct
> rte_eth_dev *dev,
> >   		 */
> >   		ad->rx_bulk_alloc_allowed = true;
> >   		ad->rx_vec_allowed = true;
> > +
> > +		/* Check if users wanted to disable vector RX functions */
> > +		i40e_disable_vec_rx(dev);
> > +
> 
> Ditto, error should be propagated.

Likewise, agreed, done and queued up for v2.

> 
> >   		dev->data->scattered_rx = use_scattered_rx;
> >   		if (use_def_burst_func)
> >   			ad->rx_bulk_alloc_allowed = false;
> >